Evolution of the structure and hardness of nickel upon cold and low-temperature deformation under pressure

Effect of dynamic recovery on structure formation in nickel upon high-pressure torsion and subsequent annealing

“…The stationary stage of deformation is provided via the developments of the dynamic relaxation process. In literature, some suppositions are made that the part of this relaxation process can be taken by the dynamic recovery [6,8,9,17] or dynamic recrystallization [10], or by both these processes [7].…”

“…In all these research works, after a certain significant strain, structure and hardness of nickel stopped changing. In the author's opinion [6][7][8][9][10], this may be caused by a stationary stage of dynamic recovery or dynamic recrystallization. The dynamic processes of recovery and recrystallization should decrease the amount of defects in the structure.…”

“…Thus, the transition of nickel structure into the SMС state corresponds to leveling off of the deformation, which was multiply reported on by other researchers as well. This can be related to the development of dynamic recovery or recrystallization processes [2,[6][7][8][9][10]. In the course of these processes, not only the rate of deformation hardening should reduce but the stored energy of deformation as well [31].…”

“…Later on, many works devoted to polycrystalline nickel subjected to SPD were published [6][7][8][9][10][11][12][13][14][15][16][17][18]. In all these research works, after a certain significant strain, structure and hardness of nickel stopped changing.…”

“…Conventionally, such structures are produced by severe plastic deformation (SPD), in particular, by high-pressure torsion (HPT). A great number of works have been devoted to studying nickel, which is a convenient object for such research works [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”